Role of ErbB4 in breast cancer

HER3 receptor and its role in the therapeutic management of metastatic breast cancer

Metastatic breast cancer (mBC) poses a significant threat to women's health and is a major cause of malignant neoplasms in women. Human epidermal growth factor receptor (HER)3, an integral member of the ErbB/HER receptor tyrosine kinase family, is a crucial activator of the phosphoinositide-3 kinase/protein kinase B signaling pathway. HER3 overexpression significantly contributes to the development of resistance to drugs targeting other HER receptors, such as HER2 and epidermal growth factor receptors, and plays a crucial role in the onset and progression of mBC. Recently, numerous HER3-targeted therapeutic agents, such as monoclonal antibodies (mAbs), bispecific antibodies (bAbs), and antibody-drug conjugates (ADCs), have emerged. However, the efficacy of HER3-targeted mAbs and bAbs is limited when used individually, and their combination may result in toxic adverse effects. On the other hand, ADCs are cytotoxic to cancer cells and can bind to target cells through antibodies, which highlights their use in targeted HER3 therapy for mBC. This review provides an overview of recent advancements in HER3 research, historical initiatives, and innovative approaches in targeted HER3 therapy for metastatic breast cancer. Evaluating the advantages and disadvantages of current methods may yield valuable insights and lessons.

HER4 Affects Sensitivity to Tamoxifen and Abemaciclib in Luminal Breast Cancer Cells and Restricts Tumor Growth in MCF-7-Based Humanized Tumor Mice

The impact of the HER4 receptor on the growth and treatment of estrogen receptor-positive breast cancer is widely uncertain. Using CRISPR/Cas9 technology, we generated stable HER4 knockout variants derived from the HER4-positive MCF-7, T-47D, and ZR-75-1 breast cancer cell lines. We investigated tumor cell proliferation as well as the cellular and molecular mechanisms of tamoxifen, abemaciclib, AMG232, and NRG1 treatments as a function of HER4 in vitro. HER4 differentially affects the cellular response to tamoxifen and abemaciclib treatment. Most conspicuous is the increased sensitivity of MCF-7 in vitro upon HER4 knockout and the inhibition of cell proliferation by NRG1. Additionally, we assessed tumor growth and immunological effects as responses to tamoxifen and abemaciclib therapy in humanized tumor mice (HTM) based on MCF-7 HER4-wildtype and the corresponding HER4-knockout cells. Without any treatment, the enhanced MCF-7 tumor growth in HTM upon HER4 knockout suggests a tumor-suppressive effect of HER4 under preclinical but human-like conditions. This phenomenon is associated with an increased HER2 expression in MCF-7 in vivo. Independent of HER4, abemaciclib and tamoxifen treatment considerably inhibited tumor growth in these mice. However, abemaciclib-treated hormone receptor-positive breast cancer patients with tumor-associated mdm2 gene copy gains or pronounced HER4 expression showed a reduced event-free survival. Evidently, the presence of HER4 affects the efficacy of tamoxifen and abemaciclib treatment in different estrogen receptor-positive breast cancer cells, even to different extents, and is associated with unfavorable outcomes in abemaciclib-treated patients.

The impact of nitric oxide on HER family post-translational modification and downstream signaling in cancer

The human epidermal growth factor receptor (HER) family consists of four members, activated by two families of ligands. They are known for mediating cell-cell interactions in organogenesis, and their deregulation has been associated with various cancers, including breast and esophageal cancers. In particular, aberrant epidermal growth factor receptor (EGFR) and HER2 signaling drive disease progression and result in poorer patient outcomes. Nitric oxide (NO) has been proposed as an alternative activator of the HER family and may play a role in this aberrant activation due to its ability to induce s-nitrosation and phosphorylation of the EGFR. This review discusses the potential impact of NO on HER family activation and downstream signaling, along with its role in the efficacy of therapeutics targeting the family.

Aberrant expression of bone morphogenetic proteins in the disease progression and metastasis of breast cancer

Background

Bone morphogenetic proteins (BMPs) play crucial roles in the tumorigenesis and metastasis of cancers. Controversy remains about the exact implications of BMPs and their antagonists in breast cancer (BC), due to their diverse and complex biological functions and signalling. A comprehensive study of the whole family and their signalling in breast cancer is provoked.

Methods

Aberrant expression of BMP, BMP receptors and antagonists in primary tumours in breast cancer were analysed by using TCGA-BRCA and E-MTAB-6703 cohorts. Related biomarkers including ER, HER, proliferation, invasion, angiogenesis, lymphangiogenesis and bone metastasis were involved to identify the relationship with BMPs in breast cancer.

Results

The present study showed BMP8B was significantly increased in breast tumours, while BMP6 and ACVRL1 were decreased in breast cancer tissues. The expressions of BMP2, BMP6, TGFBR1 and GREM1 were significantly correlated with BC patients' poor overall survival. Aberrant expression of BMPs, together with BMP receptors, were explored in different subtypes of breast cancer according to ER, PR and HER2 status. Furthermore, higher levels of BMP2, BMP6 and GDF5 were revealed in triple negative breast cancer (TNBC) whilst BMP4, GDF15, ACVR1B, ACVR2B and BMPR1B were relatively higher in Luminal type BC. ACVR1B and BMPR1B were positively correlated with ERα but were inversely correlated with ERβ. High expression of GDF15, BMP4 and ACVR1B were associated with poorer overall survival in HER2 positive BC. BMPs also play dual roles in tumour growth and metastasis of BC.

Conclusion

A shift pattern of BMPs was showed in different subtypes of breast cancer suggesting a subtype specific involvement. It provokes more research to shed light on the exact role of these BMPs and receptors in the disease progression and distant metastasis through a regulation of proliferation, invasion and EMT.

High expression of the RET receptor tyrosine kinase and its ligand GDNF identifies a high-risk subset of estrogen receptor positive breast cancer

PURPOSE

Resistance to endocrine therapy is the primary cause of treatment failure and death in patients with ER-positive (ER +)/luminal breast cancer. Expression and activation of the RET receptor tyrosine kinase may be driving poor outcomes. We aim to identify high-risk patients and druggable pathways for biomarker-based clinical trials.

METHODS

We obtained batch-normalized mRNA expression data from Breast Invasive Carcinoma-The Cancer Genome Atlas, PanCancer Atlas (BRCA-TCGA). To determine clinically significant cutoffs for RET expression, patients were grouped at different thresholds for Kaplan-Meier plotting. Differential gene expression (DGE) analysis and enrichment for gene sets was performed. transcriptomic dataset of antiestrogen-treated ER + tumors stratified by clinical response was then analyzed.

RESULTS

High RET expression was associated with worse outcomes in patients with ER + tumors, and stratification was enhanced by incorporating GDNF expression. High RET/GDNF patients had significantly lower overall survival (HR = 2.04, p = 0.012), progression-free survival (HR = 2.87, p < 0.001), disease-free survival (HR = 2.67, p < 0.001), and disease-specific survival (HR = 3.53, p < 0.001) than all other ER + patients. High RET/GDNF tumors were enriched for estrogen-independent signaling and targetable pathways including NTRK, PI3K, and KRAS. Tumors with adaptive resistance to endocrine therapy were enriched for gene expression signatures of high RET/GDNF primary tumors.

CONCLUSION

Expression and activation of the RET receptor tyrosine kinase may be driving poor outcomes in some patients with ER + breast cancer. ER + patients above the 75th percentile may benefit from clinical trials with tyrosine kinase inhibitors.

Identification of Cancer Driver Genes by Integrating Multiomics Data with Graph Neural Networks

Cancer is a heterogeneous disease that is driven by the accumulation of both genetic and nongenetic alterations, so integrating multiomics data and extracting effective information from them is expected to be an effective way to predict cancer driver genes. In this paper, we first generate comprehensive instructive features for each gene from genomic, epigenomic, transcriptomic levels together with protein–protein interaction (PPI)-networks-derived attributes and then propose a novel semisupervised deep graph learning framework GGraphSAGE to predict cancer driver genes according to the impact of the alterations on a biological system. When applied to eight tumor types, experimental results suggest that GGraphSAGE outperforms several state-of-the-art computational methods for driver genes identification. Moreover, it broadens our current understanding of cancer driver genes from multiomics level and identifies driver genes specific to the tumor type rather than pan-cancer. We expect GGraphSAGE to open new avenues in precision medicine and even further predict drivers for other complex diseases.

To Investigate Growth Factor Receptor Targets and Generate Cancer Targeting Inhibitors

Receptor tyrosine kinase (RTK) regulates multiple pathways, including Mitogenactivated protein kinases (MAPKs), PI3/AKT, JAK/STAT pathway, etc. which has a significant role in the progression and metastasis of tumor. As RTK activation regulates numerous essential bodily processes, including cell proliferation and division, RTK dysregulation has been identified in many types of cancers. Targeting RTK is a significant challenge in cancer due to the abnormal upregulation and downregulation of RTK receptors subfamily EGFR, FGFR, PDGFR, VEGFR, and HGFR in the progression of cancer, which is governed by multiple RTK receptor signalling pathways and impacts treatment response and disease progression. In this review, an extensive focus has been carried out on the normal and abnormal signalling pathways of EGFR, FGFR, PDGFR, VEGFR, and HGFR and their association with cancer initiation and progression. These are explored as potential therapeutic cancer targets and therefore, the inhibitors were evaluated alone and merged with additional therapies in clinical trials aimed at combating global cancer.

Identification of potential target genes of honokiol in overcoming breast cancer resistance to tamoxifen

Background

Honokiol (HON) inhibits epidermal growth factor receptor (EGFR) signaling and increases the activity of erlotinib, an EGFR inhibitor, in human head and neck cancers. In this study, using a bioinformatics approach and in vitro experiments, we assessed the target genes of HON against breast cancer resistance to tamoxifen (TAM).

Materials and methods

Microarray data were obtained from GSE67916 and GSE85871 datasets to identify differentially expressed genes (DEGs). DEGs common between HON-treated and TAM-resistant cells were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses and protein-protein interaction (PPI) networks were constructed. Selected genes were analyzed for genetic alterations, expression, prognostic value, and receiver operating characteristics (ROC). TAM-resistant MCF-7 (MCF-7 TAM-R) cells were generated and characterized for their resistance toward TAM. A combination of HON and TAM was used for cytotoxicity and gene expression analyses. Molecular docking was performed using the Molecular Operating Environment software.

Results

PPI network analysis revealed that FN1, FGFR2, and RET were the top three genes with the highest scores. A genetic alteration study of potential target genes revealed MMP16 and ERBB4 as the genes with the highest alterations among the breast cancer samples. Pathway enrichment analysis of FGFR2, RET, ERBB4, SOX2, FN1, and MMP16 showed that the genetic alterations herein were likely to impact the RTK-Ras pathway. The expression levels of RET, MMP16, and SOX2 were strongly correlated with prognostic power, with areas under the ROC curves (AUC) ​​of 1, 0.8, and 0.8, respectively. The HON and TAM combination increased TAM cytotoxicity in MCF-7 TAM-R cells by regulating the expression of potential target genes ret, ERBB4, SOX2, and FN1, as well as the TAM resistance regulatory genes including HES1, VIM, PCNA, TP53, and CASP7. Molecular docking results indicated that HON tended to bind RET, ErbB4, and the receptor protein Notch1 ankyrin domain more robustly than its native ligand.

Conclusion

HON could overcome breast cancer resistance to TAM, potentially by targeting FGFR2, RET, ERBB4, MMP16, FN1, and SOX2. However, further studies are required to validate these results.

Choice of High-Throughput Proteomics Method Affects Data Integration with Transcriptomics and the Potential Use in Biomarker Discovery

In recent years, several advances have been achieved in breast cancer (BC) classification and treatment. However, overdiagnosis, overtreatment, and recurrent disease are still significant causes of complication and death. Here, we present the development of a protocol aimed at parallel transcriptome and proteome analysis of BC tissue samples using mass spectrometry, via Data Dependent and Independent Acquisitions (DDA and DIA). Protein digestion was semi-automated and performed on flowthroughs after RNA extraction. Data for 116 samples were acquired in DDA and DIA modes and processed using MaxQuant, EncyclopeDIA, or DIA-NN. DIA-NN showed an increased number of identified proteins, reproducibility, and correlation with matching RNA-seq data, therefore representing the best alternative for this setup. Gene Set Enrichment Analysis pointed towards complementary information being found between transcriptomic and proteomic data. A decision tree model, designed to predict the intrinsic subtypes based on differentially abundant proteins across different conditions, selected protein groups that recapitulate important clinical features, such as estrogen receptor status, HER2 status, proliferation, and aggressiveness. Taken together, our results indicate that the proposed protocol performed well for the application. Additionally, the relevance of the selected proteins points to the possibility of using such data as a biomarker discovery tool for personalized medicine.

The lysosome as a novel therapeutic target of EGFR-mediated tumor inflammation

EGFR-mediated tumors have been targeted to overcome several different malignant cancers. EGFR overexpression and mutations are directly related to the malignancy, which makes the therapy more complicated. One reason for the malignancy is the induction of AP1 followed by inflammation via IL-6 secretion. Current therapeutic strategies to overcome EGFR-mediated tumors are tyrosine kinase inhibitors (TKIs), anti-EGFR monoclonal antibodies, and the combination of these two agents with classic chemotherapy or immune checkpoint inhibitors (ICIs). Although the strategies are straightforward and have shown promising efficacy in several studies, there are still hurdles to overcoming the adverse effects and limited efficacy. This study reviews the current therapeutic strategies to target EGFR family members, how they work, and their effects and limitations. We also suggest developing novel strategies to target EGFR-mediated tumors in a novel approach. A lysosome is the main custodial staff to discard unwanted amounts of EGFR and other receptor tyrosine kinase molecules. Targeting this organelle may be a new approach to overcoming EGFR-mediated cancers.

"Shedding" light on HER4 signaling in normal and malignant breast tissues

Receptor Tyrosine Kinases of the Epidermal Growth Factor Receptor Family play a pivotal role as drivers of carcinogenesis and uncontrolled cell growth for a variety of malignancies, not least for breast cancer. Besides the estrogen receptor, the HER2 receptor was and still is a representative marker for advanced taxonomic sub-differentiation of breast cancer and emerged as one of the first therapeutic targets for antibody based therapies. Since the approval of trastuzumab for the therapy of HER2-positive breast cancer in 1998 anti-HER2 treatment strategies are being modified, refined, and successfully combined with complementary treatments, nevertheless there is still potential for improvement. The HER2 relatives, namely HER1 (i.e., EGFR), HER3 and HER4 share a high degree of molecular homology and together form a functional unit for signal transmission. Under regular conditions, receptor coexpression patterns and receptor interaction represent key parameters for signaling robustness, which ensures cellular growth control and enables tissue differentiation. In addition, treatment efficiency of e.g., an anti-HER2 targeting is substantially determined by the expression pattern of HER receptors on target cells. Within the receptor family, the HER4 plays a particular role and is engaged in exceptional signaling activities. A favorable prognostic impact has been attributed to HER4 expression in breast cancer under specific molecular conditions. HER4-specific cellular effects are initially determined by a ligand-dependent or -independent receptor activation. Essential processes as cell growth and proliferation, cell differentiation, and apoptotic cell death can be initiated by this receptor. This review gives an overview of the role of HER4 in normal and malignant breast epithelial cells and tissues. Specific mechanism of HER4 activation and subsequent intracellular signaling will be described by taking a focus on effects provoked by receptor shedding. HER4 activities and specific effects will be correlated to breast cancer subtypes and the impact of HER4 on course and outcome of disease will be considered. Moreover, current and potential therapeutic approaches will be discussed.

Embryonic Programs in Cancer and Metastasis—Insights From the Mammary Gland

Cancer is characterized as a reversion of a differentiated cell to a primitive cell state that recapitulates, in many aspects, features of embryonic cells. This review explores the current knowledge of developmental mechanisms that are essential for embryonic mouse mammary gland development, with a particular focus on genes and signaling pathway components that are essential for the induction, morphogenesis, and lineage specification of the mammary gland. The roles of these same genes and signaling pathways in mammary gland or breast tumorigenesis and metastasis are then summarized. Strikingly, key embryonic developmental pathways are often reactivated or dysregulated during tumorigenesis and metastasis in processes such as aberrant proliferation, epithelial-to-mesenchymal transition (EMT), and stem cell potency which affects cellular lineage hierarchy. These observations are in line with findings from recent studies using lineage tracing as well as bulk- and single-cell transcriptomics that have uncovered features of embryonic cells in cancer and metastasis through the identification of cell types, cell states and characterisation of their dynamic changes. Given the many overlapping features and similarities of the molecular signatures of normal development and cancer, embryonic molecular signatures could be useful prognostic markers for cancer. In this way, the study of embryonic development will continue to complement the understanding of the mechanisms of cancer and aid in the discovery of novel therapeutic targets and strategies.

Neuregulin 4 Boosts the Efficacy of Anti-ERBB2 Neutralizing Antibodies

ERBB4 is a tyrosine kinase receptor reported to exert both oncogenic and tumor suppressor activities. These paradoxical effects were suggested to stem from different ERBB4 homo-/hetero-dimers and/or isoforms. By stratifying breast cancer patients for clinical and molecular subtypes and ERBB4 mRNA abundance, we here report that higher ERBB4 levels correlate with longer relapse-free survival in breast cancer patients of HER2-enriched and luminal A molecular subtypes, proposing a cancer-protecting role for this receptor in these specific subgroups. We also observed that HER2-enriched breast cancers express intermediate ERBB4 mRNA levels compared to luminal and triple-negative/basal-like subgroups, which displayed the highest and the lowest levels, respectively. Inspired by these clinical data, we tested the activation of ERBB4 by Neuregulins as a potential anticancer strategy for HER2+ breast cancers. To this end, we employed two HER2+ breast cancer cellular models (BT474 and SKBR3), which express intermediate/high and low ERBB4 levels, respectively. Cell proliferation and motility were evaluated on these cellular models following treatments with Neuregulin 1 (NRG1), which activates both ERBB3 and ERBB4, or Neuregulin 4 (NRG4), which specifically activates ERBB4. Both NRG1 and NRG4 were used alone or in combination with anti-ERBB2 neutralizing antibodies, namely trastuzumab and pertuzumab. In vitro treatment with NRG1 on BT474 cells restrained cell growth and reduced the anti-proliferative efficacy of trastuzumab. In contrast, treatment with NRG1 on SKBR3 cells increased cell proliferation and migration, and partially or completely impaired the anti-proliferative/anti-migratory action of trastuzumab and/or pertuzumab. Importantly, in both the cell lines, treatment with NRG4 robustly potentiated the anti-proliferative action of trastuzumab and pertuzumab. Collectively, our data in HER2+ breast cancer cells highlight that NRG1 may exert both pro- and anti-proliferative effects, and may reduce the efficacy of anti-HER2 agents, whereas NRG4 may boost the anti-proliferative effects of anti-ERBB2 agents. We propose a provocative paradigm shift in the field of growth factors in cancer progression, suggesting the administration of ERBB4 ligands, such as Neuregulin 4, as a strategy to improve the efficacy of anti-ERBB2 agents.

The HER family as therapeutic targets in colorectal cancer

The human epidermal growth factor receptor (HER, ErbB) family has four members, epidermal growth factor receptor (EGFR), HER2, HER3, and HER4. Although distinct in ligands and functions, all of the HER family members are receptor tyrosine kinases playing important roles in the pathogenesis of cancers. In the era of precision medicine, the HER family is one of the most important and successful cancer therapeutic targets, hallmarked by the approval of anti-EGFR therapies for the treatment of colorectal cancer and non-small cell lung cancer, and anti-HER2 therapies for the treatment of breast cancer and gastric cancer. This review briefly discusses how HER family members were discovered, their functions and roles in cancer, and most importantly, the developmental history and recent updates of therapies targeting HER family members, with colorectal cancer as a focus. We also discussed the patient selection and drug resistance to anti-EGFR therapies in the treatment of colorectal cancer.

Effects of H2O2 Treatment Combined With PI3K Inhibitor and MEK Inhibitor in AGS Cells: Oxidative Stress Outcomes in a Model of Gastric Cancer

Gastric cancer is worldwide the fifth and third cancer for incidence and mortality, respectively. Stomach wall is daily exposed to oxidative stress and BER system has a key role in the defense from oxidation-induced DNA damage, whilst ErbB receptors have important roles in the pathogenesis of cancer. We used AGS cells as an aggressive gastric carcinoma cell model, treated with H₂O₂ alone or combined with ErbB signaling pathway inhibitors, to evaluate the effects of oxidative stress in gastric cancer, focusing on the modulation of ErbB signaling pathways and their eventual cross-talk with BER system. We showed that treatment with H₂O₂ combined with PI3K/AKT and MEK inhibitors influenced cell morphology and resulted in a reduction of cancer cell viability. Migration ability was reduced after H₂O₂ treatment alone or combined with MEK inhibitor and after PI3K/AKT inhibitor alone. Western blotting analysis showed that oxidative stress stimulated EGFR pathway favoring the MAPKs activation at the expense of PI3K/AKT pathway. Gene expression analysis by RT-qPCR showed ErbB2 and OGG1 increase under oxidative stress conditions. Therefore, we suggest that in AGS cells a pro-oxidant treatment can reduce gastric cancer cell growth and migration via a different modulation of PI3K and MAPKs pathways. Moreover, the observed ErbB2 and OGG1 induction is a cellular response to protect the cells from H₂O₂-induced cell death. In conclusion, to tailor specific combinations of therapies and to decide which strategy to use, administration of a chemotherapy that increases intracellular ROS to toxic levels, might not only be dependent on the tumor type, but also on the molecular targeting therapy used.

Gene expression trend changes in breast cancer populations over two decades: insights from The Cancer Genome Atlas database

BACKGROUND

Breast cancer has remained the most common malignancy in women over the past two decades. As lifestyle and living environments have changed, alterations to the disease spectrum have inevitably occurred in this time. As molecular profiling has become a routine diagnostic and objective indicator of breast cancer etiology, we analyzed changes in gene expression in breast cancer populations over two decades using The Cancer Genome Atlas database.

METHODS

We performed Heatmap and Venn diagram analyses to identify constantly up- and down-regulated genes in breast cancer patients of this cohort. We used Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses to visualize associated functional pathways.

RESULTS

We determined that three oncogenes, PD-L2, ETV5, and MTOR and 113 long intergenic non-coding RNAs (lincRNAs) were constantly up-regulated, whereas two oncogenes, BCR and GTF2I, one tumor suppression gene MEN1, and 30 lincRNAs were constantly down-regulated. Up-regulated genes were enriched in "focal adhesion" and "PI3K-Akt signaling" pathways, etc., and down-regulated genes were significantly enriched in "metabolic pathways" and "viral myocarditis". Eight up-regulated genes exhibited doubled or higher expression and the expression of three down-regulated genes was halved or lowered and correlated with long-term survival.

CONCLUSIONS

In this study, we found that gene expression and molecular pathway enrichments are constantly changing with time, importantly, some altered genes were associated with prognostics and are potential therapeutic targets, suggesting that the current molecular subtyping system must be updated to keep pace with this dynamic change.

It Takes More than Two to Tango: Complex, Hierarchal, and Membrane-Modulated Interactions in the Regulation of Receptor Tyrosine Kinases

The search for an understanding of how cell fate and motility are regulated is not a purely scientific undertaking, but it can also lead to rationally designed therapies against cancer. The discovery of tyrosine kinases about half a century ago, the subsequent characterization of certain transmembrane receptors harboring tyrosine kinase activity, and their connection to the development of human cancer ushered in a new age with the hope of finding a treatment for malignant diseases in the foreseeable future. However, painstaking efforts were required to uncover the principles of how these receptors with intrinsic tyrosine kinase activity are regulated. Developments in molecular and structural biology and biophysical approaches paved the way towards better understanding of these pathways. Discoveries in the past twenty years first resulted in the formulation of textbook dogmas, such as dimerization-driven receptor association, which were followed by fine-tuning the model. In this review, the role of molecular interactions taking place during the activation of receptor tyrosine kinases, with special attention to the epidermal growth factor receptor family, will be discussed. The fact that these receptors are anchored in the membrane provides ample opportunities for modulatory lipid-protein interactions that will be considered in detail in the second part of the manuscript. Although qualitative and quantitative alterations in lipids in cancer are not sufficient in their own right to drive the malignant transformation, they both contribute to tumor formation and also provide ways to treat cancer. The review will be concluded with a summary of these medical aspects of lipid-protein interactions.

miR-551b is Associated with the Poor Prognosis and Malignant Development of Papillary Thyroid Cancer Through Regulating ERBB4

The function of miR-551b has been widely reported in various human cancers, and its dysregulation in papillary thyroid cancer (PTC) has also been disclosed, implying its potential regulator role in PTC. The aim of the study was to evaluate the function of miR-551b in PTC development and its potential mechanism. miR-551b was evaluated in PTC tissues and cells by RT-qPCR and associated with the clinicopathological features of patients. The biological effect of miR-551b on cellular processes of PTC was assessed with the CCK8 proliferation assay and the Transwell migration and invasion assay. The potential molecular mechanism was estimated with the dual-luciferase reporter assay. miR-551b was significantly upregulated in PTC, which showed a close relationship with the malignancy and development of PTC patients. miR-551b served as a prognostic biomarker negatively related to patients' survival together with the TNM stage. The overexpression of miR-551b exerted promoted effect on the development-related cellular processes of PTC, which was reversed by the overexpression of ERBB4. In conclusion, miR-551b could predict the poor prognosis of PTC patients and serve as a tumor promoter via suppressing ERBB4.

The Yin and Yang of ERBB4: Tumor Suppressor and Oncoprotein

ERBB4 (HER4) is a member of the ERBB family of receptor tyrosine kinases, a family that includes the epidermal growth factor receptor (EGFR/ERBB1/HER1), ERBB2 (Neu/HER2), and ERBB3 (HER3). EGFR and ERBB2 are oncoproteins and validated targets for therapeutic intervention in a variety of solid tumors. In contrast, the role that ERBB4 plays in human malignancies is ambiguous. Thus, here we review the literature regarding ERBB4 function in human malignancies. We review the mechanisms of ERBB4 signaling with an emphasis on mechanisms of signaling specificity. In the context of this signaling specificity, we discuss the hypothesis that ERBB4 appears to function as a tumor suppressor protein and as an oncoprotein. Next, we review the literature that describes the role of ERBB4 in tumors of the bladder, liver, prostate, brain, colon, stomach, lung, bone, ovary, thyroid, hematopoietic tissues, pancreas, breast, skin, head, and neck. Whenever possible, we discuss the possibility that ERBB4 mutants function as biomarkers in these tumors. Finally, we discuss the potential roles of ERBB4 mutants in the staging of human tumors and how ERBB4 function may dictate the treatment of human tumors. SIGNIFICANCE STATEMENT: This articles reviews ERBB4 function in the context of the mechanistic model that ERBB4 homodimers function as tumor suppressors, whereas ERBB4-EGFR or ERBB4-ERBB2 heterodimers act as oncogenes. Thus, this review serves as a mechanistic framework for clinicians and scientists to consider the role of ERBB4 and ERBB4 mutants in staging and treating human tumors.

A Review of HER4 (ErbB4) Kinase, Its Impact on Cancer, and Its Inhibitors

HER4 is a receptor tyrosine kinase that is required for the evolution of normal body systems such as cardiovascular, nervous, and endocrine systems, especially the mammary glands. It is activated through ligand binding and activates MAPKs and PI3K/AKT pathways. HER4 is commonly expressed in many human tissues, both adult and fetal. It is important to understand the role of HER4 in the treatment of many disorders. Many studies were also conducted on the role of HER4 in tumors and its tumor suppressor function. Mostly, overexpression of HER4 kinase results in cancer development. In the present article, we reviewed the structure, location, ligands, physiological functions of HER4, and its relationship to different cancer types. HER4 inhibitors reported mainly from 2016 to the present were reviewed as well.

Analysis of SYK Gene as a Prognostic Biomarker and Suggested Potential Bioactive Phytochemicals as an Alternative Therapeutic Option for Colorectal Cancer: An In-Silico Pharmaco-Informatics Investigation

BACKGROUND

SYK gene regulates the expression of SYK kinase (Spleen tyrosine kinase), an important non-receptor protein-tyrosine kinase for immunological receptor-mediated signaling, which is also considered a tumor growth metastasis initiator. An onco-informatics analysis was adopted to evaluate the expression and prognostic value of the SYK gene in colorectal cancer (CRC), the third most fatal cancer type; of late, it may be a biomarker as another targeted site for CRC. In addition, identify the potential phytochemicals that may inhibit the overexpression of the SYK kinase protein and minimize the human CRC.

MATERIALS & METHODS

The differential expression of the SYK gene was analyzed using several transcriptomic databases, including Oncomine, UALCAN, GENT2, and GEPIA2. The server cBioPortal was used to analyze the mutations and copy number alterations, whereas GENT2, Gene Expression Profiling Interactive Analysis (GEPIA), Onco-Lnc, and PrognoScan were used to examine the survival rate. The protein-protein interaction network of SYK kinase and its co-expressed genes was conducted via Gene-MANIA. Considering the SYK kinase may be the targeted site, the selected phytochemicals were assessed by molecular docking using PyRx 0.8 packages. Molecular interactions were also observed by following the Ligplot+ version 2.2. YASARA molecular dynamics simulator was applied for the post-validation of the selected phytochemicals.

RESULTS

Our result reveals an increased level of mRNA expression of the SYK gene in colorectal adenocarcinoma (COAD) samples compared to those in normal tissues. A significant methylation level and various genetic alterations recurrence of the SYK gene were analyzed where the fluctuation of the SYK alteration frequency was detected across different CRC studies. As a result, a lower level of SYK expression was related to higher chances of survival. This was evidenced by multiple bioinformatics platforms and web resources, which demonstrated that the SYK gene can be a potential biomarker for CRC. In this study, aromatic phytochemicals, such as kaempferol and glabridin that target the macromolecule (SYK kinase), showed higher stability than the controls, and we have estimated that these bioactive potential phytochemicals might be a useful option for CRC patients after the clinical trial.

CONCLUSIONS

Our onco-informatics investigation suggests that the SYK gene can be a potential prognostic biomarker of CRC. On the contrary, SYK kinase would be a major target, and all selected compounds were validated against the protein using in-silico drug design approaches. Here, more in vitro and in vivo analysis is required for targeting SYK protein in CRC.

Molecular Functions of WWOX Potentially Involved in Cancer Development

The WW domain-containing oxidoreductase gene (WWOX) was cloned 21 years ago as a putative tumor suppressor gene mapping to chromosomal fragile site FRA16D. The localization of WWOX in a chromosomal region frequently altered in human cancers has initiated multiple current studies to establish its role in this disease. All of this work suggests that WWOX, due to its ability to interact with a large number of partners, exerts its tumor suppressive activity through a wide variety of molecular actions that are mostly cell specific.

Application of 1,4-Oxazinone Precursors to the Construction of Pyridine Derivatives by Tandem Intermolecular Cycloaddition/Cycloreversion

This study reveals a new method for the preparation of 1,4-oxazinone derivatives by Staudinger reductive cyclization of functionalized vinyl azide precursors. The resulting oxazinone derivatives prepared in this manner were intercepted with terminal alkyne substrates through an intermolecular cycloaddition/cycloreversion sequence to afford polysubstituted pyridine products. Alkyne substrates bearing propargyl oxygen substitution showed good regioselectivity in the cycloaddition operation selectively affording 2,4,6-substituted pyridines. Application of this chemistry to the synthesis of an ErbB4 receptor inhibitor is also described.

Antitumour immunity regulated by aberrant ERBB family signalling

Aberrant signalling of ERBB family members plays an important role in tumorigenesis and in the escape from antitumour immunity in multiple malignancies. Molecular-targeted agents against these signalling pathways exhibit robust clinical efficacy, but patients inevitably experience acquired resistance to these molecular-targeted therapies. Although cancer immunotherapies, including immune checkpoint inhibitors (ICIs), have shown durable antitumour response in a subset of the treated patients in multiple cancer types, clinical efficacy is limited in cancers harbouring activating gene alterations of ERBB family members. In particular, ICI treatment of patients with non-small cell lung cancers with epidermal growth factor receptor (EGFR) alterations and breast cancers with HER2 alterations failed to show clinical benefits, suggesting that EGFR and HER2 signalling may have an essential role in inhibiting antitumour immune responses. Here, we discuss the mechanisms by which the signalling of ERBB family members affects not only autonomous cancer hallmarks, such as uncontrolled cell proliferation, but also antitumour immune responses in the tumour microenvironment and the potential application of immune-genome precision medicine into immunotherapy and molecular-targeted therapy focusing on the signalling of ERBB family members.

Her4 promotes cancer metabolic reprogramming via the c-Myc-dependent signaling axis

Despite the growing recognition of metabolic reprogramming as an important hallmark of cancer in the past few years, the molecular mechanisms underlying metabolic alterations during tumorigenesis remain unclear. In this study, we identified a critical role of Her4 in rewiring cancer metabolism toward tumor-promoting metabolic processes, including increased glycolysis, glutaminolysis, mitochondrial biogenesis, and oxidative phosphorylation, which may in part cooperate to promote tumorigenesis. We found that overexpression of Her4 promoted the stabilization of c-Myc through a CIP2A-mediated increase in c-Myc^S62 phosphorylation and GSK3β-mediated decrease in c-Myc^T58 phosphorylation, both of which decreased c-Myc degradation. Furthermore, Her4 was found to increase glucose uptake and tumor growth in an osteosarcoma xenograft model. Overall, these findings provide a better understanding of the involvement of Her4 in tumorigenesis and document its potential role in metabolic reprogramming for the first time. We believe that our study might lead to promising opportunities for targeted metabolic therapy for cancer.

An integrative ENCODE resource for cancer genomics

ENCODE comprises thousands of functional genomics datasets, and the encyclopedia covers hundreds of cell types, providing a universal annotation for genome interpretation. However, for particular applications, it may be advantageous to use a customized annotation. Here, we develop such a custom annotation by leveraging advanced assays, such as eCLIP, Hi-C, and whole-genome STARR-seq on a number of data-rich ENCODE cell types. A key aspect of this annotation is comprehensive and experimentally derived networks of both transcription factors and RNA-binding proteins (TFs and RBPs). Cancer, a disease of system-wide dysregulation, is an ideal application for such a network-based annotation. Specifically, for cancer-associated cell types, we put regulators into hierarchies and measure their network change (rewiring) during oncogenesis. We also extensively survey TF-RBP crosstalk, highlighting how SUB1, a previously uncharacterized RBP, drives aberrant tumor expression and amplifies the effect of MYC, a well-known oncogenic TF. Furthermore, we show how our annotation allows us to place oncogenic transformations in the context of a broad cell space; here, many normal-to-tumor transitions move towards a stem-like state, while oncogene knockdowns show an opposing trend. Finally, we organize the resource into a coherent workflow to prioritize key elements and variants, in addition to regulators. We showcase the application of this prioritization to somatic burdening, cancer differential expression and GWAS. Targeted validations of the prioritized regulators, elements and variants using siRNA knockdowns, CRISPR-based editing, and luciferase assays demonstrate the value of the ENCODE resource.

The guanine nucleotide exchange factor VAV3 participates in ERBB4-mediated cancer cell migration

ERBB4 is a member of the epidermal growth factor receptor (EGFR)/ERBB subfamily of receptor tyrosine kinases that regulates cellular processes including proliferation, migration, and survival. ERBB4 signaling is involved in embryogenesis and homeostasis of healthy adult tissues, but also in human pathologies such as cancer, neurological disorders, and cardiovascular diseases. Here, an MS-based analysis revealed the Vav guanine nucleotide exchange factor 3 (VAV3), an activator of Rho family GTPases, as a critical ERBB4-interacting protein in breast cancer cells. We confirmed the ERBB4-VAV3 interaction by targeted MS and coimmunoprecipitation experiments and further defined it by demonstrating that kinase activity and Tyr-1022 and Tyr-1162 of ERBB4, as well as the intact phosphotyrosine-interacting SH2 domain of VAV3, are necessary for this interaction. We found that ERBB4 stimulates tyrosine phosphorylation of the VAV3 activation domain, known to be required for guanine nucleotide exchange factor (GEF) activity of VAV proteins. In addition to VAV3, the other members of the VAV family, VAV1 and VAV2, also coprecipitated with ERBB4. Analyses of the effects of overexpression of dominant-negative VAV3 constructs or shRNA-mediated down-regulation of VAV3 expression in breast cancer cells indicated that active VAV3 is involved in ERBB4-stimulated cell migration. These results define the VAV GEFs as effectors of ERBB4 activity in a signaling pathway relevant for cancer cell migration.

The role of ErbB4 in cancer

BACKGROUND

The epidermal growth factor receptor family consists of four members, ErbB1 (epidermal growth factor receptor-1), ErbB2, ErbB3, and ErbB4, which all have been found to play important roles in tumor development. ErbB4 appears to be unique among these receptors, because it is the only member with growth inhibiting properties. ErbB4 plays well-defined roles in normal tissue development, in particular the heart, the nervous system, and the mammary gland system. In recent years, information on the role of ErbB4 in a number of tumors has emerged and its general direction points towards a tumor suppressor role for ErbB4. However, there are some controversies and conflicting data, warranting a review on this topic.

CONCLUSIONS

Here, we discuss the role of ErbB4 in normal physiology and in breast, lung, colorectal, gastric, pancreatic, prostate, bladder, and brain cancers, as well as in hepatocellular carcinoma, cholangiocarcinoma, and melanoma. Understanding the role of ErbB4 in cancer is not only important for the treatment of tumors, but also for the treatment of other disorders in which ErbB4 plays a major role, e.g. cardiovascular disease.

Machine learning on genome-wide association studies to predict the risk of radiation-associated contralateral breast cancer in the WECARE Study

The purpose of this study was to identify germline single nucleotide polymorphisms (SNPs) that optimally predict radiation-associated contralateral breast cancer (RCBC) and to provide new biological insights into the carcinogenic process. Fifty-two women with contralateral breast cancer and 153 women with unilateral breast cancer were identified within the Women’s Environmental Cancer and Radiation Epidemiology (WECARE) Study who were at increased risk of RCBC because they were ≤ 40 years of age at first diagnosis of breast cancer and received a scatter radiation dose > 1 Gy to the contralateral breast. A previously reported algorithm, preconditioned random forest regression, was applied to predict the risk of developing RCBC. The resulting model produced an area under the curve (AUC) of 0.62 (p = 0.04) on hold-out validation data. The biological analysis identified the cyclic AMP-mediated signaling and Ephrin-A as significant biological correlates, which were previously shown to influence cell survival after radiation in an ATM-dependent manner. The key connected genes and proteins that are identified in this analysis were previously identified as relevant to breast cancer, radiation response, or both. In summary, machine learning/bioinformatics methods applied to genome-wide genotyping data have great potential to reveal plausible biological correlates associated with the risk of RCBC.

ErbB4 3'-UTR Variant (c.*3622A>G) is Associated with ER/PR Negativity and Advanced Breast Cancer

A genetic variant may alter a gene expression level and as a result be associated with pathological characteristics in breast cancer. In this research, the frequency and association of the ErbB4 3'-untranslated region (3'-UTR) variant, rs12471583 (c.*3622A>G) was studied in an Iranian breast cancer patients. In silico assessment was performed to predict the function of the rs12471583 variant located on the 3'-UTR of ErbB4. Furthermore, as a case-control study, this polymorphism was genotyped in 243 breast cancer patients and non-cancerous controls using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. The Armitage's trend test and regular association tests were performed to analyze a possible association between the rs12471583 and risk of breast cancer and its relevant pathological traits. The bioinformatics analysis predicted that the rs12471583 SNP is located on the four miRNA binding sites, including miR-511-5p, miR-4659a-5p, miR-4659b-5p, and miR-6830-3p. According to logistic regression tests, the G allele is negatively associated with ER- (OR = 0.20, 95% C.I. = 0.04-0.93, p = 0.026), PR- (OR = 0.31, 95% C.I. = 0.10-0.98, p = 0.039), ER-/PR- (OR = 0.20, 95% C.I. = 0.04-0.93, p = 0.026), and advanced breast cancer (OR = 0.40, 95% C.I. = 0.18-0.85, p = 0.016). It has been found that ErbB4 expression may be linked to unfavorable outcomes in breast cancer. Likewise, our results suggest that the G allele may strengthen miRNA-ErbB4 binding efficiency and as a result reduce expression of ErbB4. This is a possible explanation for the observed association.

Stapled EGFR peptide reduces inflammatory breast cancer and inhibits additional HER-driven models of cancer

Background

The human epidermal growth factor receptor (HER) family of transmembrane tyrosine kinases is overexpressed and correlates with poor prognosis and decreased survival in many cancers. The receptor family has been therapeutically targeted, yet tyrosine kinase inhibitors (TKIs) do not inhibit kinase-independent functions and antibody-based targeting does not affect internalized receptors. We have previously demonstrated that a peptide mimicking the internal juxtamembrane domain of HER1 (EGFR; EJ1) promotes the formation of non-functional HER dimers that inhibit kinase-dependent and kinase-independent functions of HER1 (ERBB1/EGFR), HER2 (ERBB2) and HER3 (ERBB3). Despite inducing rapid HER-dependent cell death in vitro, EJ1 peptides are rapidly cleared in vivo, limiting their efficacy.

Method

To stabilize EJ1 activity, hydrocarbon staples (SAH) were added to the active peptide (SAH-EJ1), resulting in a 7.2-fold increase in efficacy and decreased in vivo clearance. Viability assays were performed across HER1 and HER2 expressing cell lines, therapeutic-resistant breast cancer cells, clinically relevant HER1-mutated lung cancer cells, and patient-derived glioblastoma cells, in all cases demonstrating improved efficacy over standard of care pan-HER therapeutics. Tumor burden studies were also performed in lung, glioblastoma, and inflammatory breast cancer mouse models, evaluating tumor growth and overall survival.

Results

When injected into mouse models of basal-like and inflammatory breast cancers, EGFRvIII-driven glioblastoma, and lung adenocarcinoma with Erlotinib resistance, tumor growth is inhibited and overall survival is extended. Studies evaluating the toxicity of SAH-EJ1 also demonstrate a broad therapeutic window.

Conclusions

Taken together, these data indicate that SAH-EJ1 may be an effective therapeutic for HER-driven cancers with the potential to eliminate triple negative inflammatory breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1939-7) contains supplementary material, which is available to authorized users.

Target HER four in breast cancer?

The HER4 receptor tyrosine kinase is known to have promiscuous activity in malignant cells, last but not least in breast cancer. Evidently, the prognostic and predictive impact of HER4 expression depends on the expression of different receptor isotypes, the way of receptor activation (ligand dependent vs. independent), and on the complex interaction of the HER4 intracellular domain (4ICD) with intracellular regulative molecules which results in either oncogenic or rather tumor suppressive HER4 activity. Recent data suggest that HER4 unfavorably affects the endocrine treatment of postmenopausal breast cancer patients with tamoxifen and therefore might represent an additional therapeutic target in luminal breast cancer.

Germline genetic variants in somatically significantly mutated genes in tumors are associated with renal cell carcinoma risk and outcome

Genome-wide association studies (GWAS) have identified 13 susceptibility loci for renal cell carcinoma (RCC). Additional genetic loci of risk remain to be explored. Moreover, the role of germline genetic variants in predicting RCC recurrence and overall survival (OS) is less understood. In this study, we focused on 127 significantly mutated genes from The Cancer Genome Atlas (TCGA) Pan-Cancer Analysis across 12 major cancer sites to identify potential genetic variants predictive of RCC risk and clinical outcomes. In a three-phase design with a total of 2657 RCC cases and 5315 healthy controls, two single nucleotide polymorphisms (SNPs) that map to PIK3CG (rs6466135:A, ORmeta = 0.85, 95% CI = 0.77-0.94, Pmeta = 1.4 × 10-3) and ATM (rs611646:T, ORmeta = 1.17, 95% CI = 1.05-1.31, Pmeta = 3.5 × 10-3) were significantly associated with RCC risk. With respect to RCC recurrence and OS, two separate datasets with a total of 661 stages I-III RCC patients (discovery: 367; validation: 294) were analyzed. The most significant association was observed for rs10932384:C (ERBB4) with both outcomes (recurrence: HRmeta = 0.52, 95% CI = 0.39-0.68, Pmeta = 3.81 × 10-6; OS: HRmeta = 0.50, 95% CI = 0.37-0.67, Pmeta = 6.00 × 10-6). In addition, six SNPs were significantly associated with either RCC recurrence or OS but not both (Pmeta < 0.01). Rs10932384:C was significantly correlated with mutation frequency of ERBB4 in clear cell RCC (ccRCC) patients (P = 0.003, Fisher's exact test). Cis-eQTL was observed for several SNPs in blood/transformed fibroblasts but not in RCC tumor tissues. In summary, we identified promising genetic predictors of recurrence and OS among RCC patients with localized disease.

A comprehensive review of heregulins, HER3, and HER4 as potential therapeutic targets in cancer

Heregulins (HRGs) bind to the receptors HER3 or HER4, induce receptor dimerization, and trigger downstream signaling that leads to tumor progression and resistance to targeted therapies. Increased expression of HRGs has been associated with worse clinical prognosis; therefore, attempts to block HRG-dependent tumor growth have been pursued. This manuscript summarizes the function and signaling of HRGs and review the preclinical evidence of its involvement in carcinogenesis, prognosis, and treatment resistance in several malignancies such as colorectal cancer, non-small cell lung cancer, ovarian cancer, and breast cancer. Agents in preclinical development and clinical trials of novel therapeutics targeting HRG-dependent signaling are also discussed, including anti-HER3 and -HER4 antibodies, anti-metalloproteinase agents, and HRG fusion proteins. Although several trials have indicated an acceptable safety profile, translating preclinical findings into clinical practice remains a challenge in this field, possibly due to the complexity of downstream signaling and patterns of HRG, HER3 and HER4 expression in different cancer subtypes. Improving patient selection through biomarkers and understanding the resistance mechanisms may translate into significant clinical benefits in the near future.

SUMOylation regulates nuclear accumulation and signaling activity of the soluble intracellular domain of the ErbB4 receptor tyrosine kinase

Erb-B2 receptor tyrosine kinase 4 (ErbB4) is a kinase that can signal via a proteolytically released intracellular domain (ICD) in addition to classical receptor tyrosine kinase-activated signaling cascades. Previously, we have demonstrated that ErbB4 ICD is posttranslationally modified by the small ubiquitin-like modifier (SUMO) and functionally interacts with the PIAS3 SUMO E3 ligase. However, direct evidence of SUMO modification in ErbB4 signaling has remained elusive. Here, we report that the conserved lysine residue 714 in the ErbB4 ICD undergoes SUMO modification, which was reversed by sentrin-specific proteases (SENPs) 1, 2, and 5. Although ErbB4 kinase activity was not necessary for the SUMOylation, the SUMOylated ErbB4 ICD was tyrosine phosphorylated to a higher extent than unmodified ErbB4 ICD. Mutation of the SUMOylation site compromised neither ErbB4-induced phosphorylation of the canonical signaling pathway effectors Erk1/2, Akt, or STAT5 nor ErbB4 stability. In contrast, SUMOylation was required for nuclear accumulation of the ErbB4 ICD. We also found that Lys-714 was located within a leucine-rich stretch, which resembles a nuclear export signal, and could be inactivated by site-directed mutagenesis. Furthermore, SUMOylation modulated the interaction of ErbB4 with chromosomal region maintenance 1 (CRM1), the major nuclear export receptor for proteins. Finally, the SUMO acceptor lysine was functionally required for ErbB4 ICD-mediated inhibition of mammary epithelial cell differentiation in a three-dimensional cell culture model. Our findings indicate that a SUMOylation-mediated mechanism regulates nuclear localization and function of the ICD of ErbB4 receptor tyrosine kinase.

ErbB Family Signalling: A Paradigm for Oncogene Addiction and Personalized Oncology

ErbB family members represent important biomarkers and drug targets for modern precision therapy. They have gained considerable importance as paradigms for oncoprotein addiction and personalized medicine. This review summarizes the current understanding of ErbB proteins in cell signalling and cancer and describes the molecular rationale of prominent cases of ErbB oncoprotein addiction in different cancer types. In addition, we have highlighted experimental technologies for the development of innovative cancer cell models that accurately predicted clinical ErbB drug efficacies. In the future, such cancer models might facilitate the identification and validation of physiologically relevant novel forms of oncoprotein and non-oncoprotein addiction or synthetic lethality. The identification of genotype-drug response relationships will further advance personalized oncology and improve drug efficacy in the clinic. Finally, we review the most important drugs targeting ErbB family members that are under investigation in clinical trials or that made their way already into clinical routine. Taken together, the functional characterization of ErbB oncoproteins have significantly increased our knowledge on predictive biomarkers, oncoprotein addiction and patient stratification and treatment.

Intrinsic Subtypes and Gene Expression Profiles in Primary and Metastatic Breast Cancer

Biological changes that occur during metastatic progression of breast cancer are still incompletely characterized. In this study, we compared intrinsic molecular subtypes and gene expression in 123 paired primary and metastatic tissues from breast cancer patients. Intrinsic subtype was identified using a PAM50 classifier and χ² tests determined the differences in variable distribution. The rate of subtype conversion was 0% in basal-like tumors, 23.1% in HER2-enriched (HER2-E) tumors, 30.0% in luminal B tumors, and 55.3% in luminal A tumors. In 40.2% of cases, luminal A tumors converted to luminal B tumors, whereas in 14.3% of cases luminal A and B tumors converted to HER2-E tumors. We identified 47 genes that were expressed differentially in metastatic versus primary disease. Metastatic tumors were enriched for proliferation-related and migration-related genes and diminished for luminal-related genes. Expression of proliferation-related genes were better at predicting overall survival in metastatic disease (OSmet) when analyzed in metastatic tissue rather than primary tissue. In contrast, a basal-like gene expression signature was better at predicting OSmet in primary disease compared with metastatic tissue. We observed correlations between time to tumor relapse and the magnitude of changes of proliferation, luminal B, or HER2-E signatures in metastatic versus primary disease. Although the intrinsic subtype was largely maintained during metastatic progression, luminal/HER2-negative tumors acquired a luminal B or HER2-E profile during metastatic progression, likely reflecting tumor evolution or acquisition of estrogen independence. Overall, our analysis revealed the value of stratifying gene expression by both cancer subtype and tissue type, providing clinicians more refined tools to evaluate prognosis and treatment. Cancer Res; 77(9); 2213-21. ©2017 AACR.

ERBB4 Expression in Ovarian Serous Carcinoma Resistant to Platinum-Based Therapy

Few data exist on the prognostic and predictive impact of erb-b2 receptor tyrosine kinase 4 (ERBB4) in ovarian cancer. Thus, we evaluated ERBB4 expression by immunohistochemistry in a tumor microarray consisting of 100 ovarian serous carcinoma specimens (50 complete responses [CRs] and 50 incomplete responses [IRs] to platinum-based therapy), 51 normal tissue controls, and 16 ovarian cancer cell lines. H scores were used to evaluate expression and were semiquantitatively classified into low, intermediate, and high categories. Category frequencies were compared between tumor specimens vs controls using an unpaired t test. Among tumors, category frequencies were compared between CR and IR to chemotherapy. Overall survival (OS) was stratified by category. In total, 74 ovarian serous carcinoma samples (32 CRs and 42 IRs), 28 normal controls, and 16 ovarian cancer cell lines were evaluable. High-level ERBB4 expression was observed at a significantly higher frequency in ovarian serous carcinoma compared with normal control tissue. Among tumor specimens, ERBB4 expression was significantly higher for those with an IR to chemotherapy compared with CR (P = .033). OS was inversely correlated with ERBB4 expression levels. Median rates of OS were 18, 22, and 58 months among high-, intermediate-, and low-expression tumors, respectively. Our results indicate that ERBB4 expression by immunohistochemistry may correlate with chemotherapy-resistant ovarian serous carcinoma and shortened OS.

KITENIN functions as a fine regulator of ErbB4 expression level in colorectal cancer via protection of ErbB4 from E3-ligase Nrdp1-mediated degradation

Understanding the complex biological functions of E3-ubiquitin ligases may facilitate the development of mechanism-based anti-cancer drugs. We recently identified that the KITENIN/ErbB4-Dvl2-c-Jun axis works as a novel unconventional downstream signal of epidermal growth factor (EGF) in colorectal cancer (CRC) tissues. Here we addressed whether E3-ubiquitin ligases are required for operation of this axis. We found that Nrdp1, an E3-ligase for ErbB3/ErbB4, interacted with KITENIN (KAI1 C-terminal interacting tetraspanin) to form a functional KITENIN/ErbB4/Nrdp1 complex and is responsible for down-regulating Dvl2 within this complex. Interestingly, ErbB4 was resistant to degradation by Nrdp1 in KITENIN/Nrdp1-co-transfected CRC cells, and KITENIN bound to the C-terminal coiled-coil domain of Nrdp1. Chemical blockade of ErbB kinase did not block the action of EGF to increase in total/phospho-ErbB4 and phospho-ERK in KITENIN/ErbB4-cotransfected cells, whereas it blocked the action of EGF in ErbB4 alone-transfected CRC cells. In human CRC tissues, higher expressions of ErbB4 and KITENIN and lower expression of Dvl2 was observed in stage IV samples than in stage I, but a low level of Nrdp1 was expressed in both stages and it did not differ significantly by stage. These results indicated that Nrdp1 is necessary for the reduction in Dvl2 to generate c-Jun in the EGF-KITENIN/ErbB4-c-Jun axis, but more importantly, elevated KITENIN protects KITENIN-bound ErbB4 from Nrdp1-mediated degradation via physical collaboration between the KITENIN/ErbB4 complex and Nrdp1, but not via modulation of ErbB kinase activity. Thus, KITENIN functions in the maintenance of a higher expression level of ErbB4 in advanced CRC tissues, independent of ubiquitin-mediated degradation via Nrdp1. © 2016 Wiley Periodicals, Inc.

Targeting HER3 using mono- and bispecific antibodies or alternative scaffolds

The human epidermal growth factor receptor 3 (HER3) has in recent years been recognized as a key node in the complex signaling network of many different cancers. It is implicated in de novo and acquired resistance against therapies targeting other growth factor receptors, e.g., EGFR, HER2, and it is a major activator of the PI3K/Akt signaling pathway. Consequently, HER3 has attracted substantial attention, and is today a key target for drugs in clinical development. Sophisticated protein engineering approaches have enabled the generation of a range of different affinity proteins targeting this receptor, including antibodies and alternative scaffolds that are either mono- or bispecific. Here, we describe HER3 and its role as a key tumor target, and give a comprehensive review of HER3-targeted proteins currently in development, including discussions on the opportunities and challenges of targeting this receptor.

Overexpression of PY1289-HER3 in sporadic pulmonary carcinoid from patients bearing MEN1 gene variants

The present study aimed to investigate the expression of human epidermal growth factor receptors (HERs) (HER1/HER2/HER3/HER4) and their phosphorylated forms (p-HER1/p-HER2/p-HER3/p-HER4) in pulmonary carcinoids (PCs). HER and p-HER protein expression was assessed by immunohistochemistry on tissue microarrays in 37 specimens of sporadic PCs, 29 typical carcinoids (TCs) and 8 atypical carcinoids (ACs). When compared with the ACs, the TCs did not exhibit any differences in terms of HER/p-HER expression. The tumors of this study have previously been characterized for the expression of menin and the mutational status of menin 1 (MEN1), a gene strongly implicated in the pathogenesis of PCs. In the present study, it was found that the cytoplasmic (‘disarrayed’), but not nuclear (‘arrayed’) expression of menin was positively correlated with HER3 (P=0.004), HER4 (P=0.015), p-HER1 (P=0.005), p-HER3 (P<0.001), and p-HER4 (P=0.001) expression. Moreover, HER3 and p-HER3 were found to be significantly more expressed in PCs with MEN1 variants, than in tumors with MEN1 wild-type (P=0.000 and P=0.025, respectively). These findings suggest the potential clinical use of HER inhibitors in the treatment of patients with PCs, particularly for individuals with p-HER3-positive PCs harboring MEN1 gene variants.

Prognostic value of ERBB4 expression in patients with triple negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is known for aggressive biologic features and poor prognosis. Epidermal growth factor receptor (EGFR) overexpression in TNBC indicates poor prognosis. However, there is no previous study of the relationship between expression of the entire human epidermal growth factor receptor (HER) family genes and patient prognosis in TNBC. Accordingly, we investigated the expression profiles of HER family genes in patients with TNBC to determine the prognostic value and clinical implications of HER family expression.

METHODS

We used the nCounter expression assay (NanoString®) to measure the expression of EGFR, erb-B2 receptor tyrosine kinase 2 (ERBB2), ERBB3, ERBB4, and estrogen receptor 1 (ESR1) genes using mRNA extracted from paraffin-embedded tumor tissues from 203 patients diagnosed with TNBC. Our data were validated using a separate cohort of 84 TNBC patients.

RESULTS

A total of 203 TNBC patients who received adjuvant chemotherapy after curative surgery from 2000 to 2004 formed the training set. The 84 TNBC patients in the validation consort were selected from breast cancer patients who received curative surgery since 2005 to 2010. Analysis of the expression profiles of the HER family genes in TNBC tissue specimens revealed that increased expression of ERBB4 was associated with poor prognosis according to survival analysis (5-year distant relapse free survival [5Y DRFS], low vs. high expression [cut-off: median]: 90.1% vs. 80.2%; p = 0.022). This trend was also observed in the validation set of TNBC patients (5Y DRFS, low vs. high: 69.4% vs. 44.7%; p = 0.053). In a multivariate Cox regression model, ERBB4 expression was identified as a indicator of long-term prognosis in patients with TNBC.

CONCLUSIONS

The expression profile of ERBB4, a member of the HER family, might serve as a prognostic marker in patients with TNBC.

Nuclear HER4 mediates acquired resistance to trastuzumab and is associated with poor outcome in HER2 positive breast cancer

The role of HER4 in breast cancer is controversial and its role in relation to trastuzumab resistance remains unclear. We showed that trastuzumab treatment and its acquired resistance induced HER4 upregulation, cleavage and nuclear translocation. However, knockdown of HER4 by specific siRNAs increased trastuzumab sensitivity and reversed its resistance in HER2 positive breast cancer cells. Preventing HER4 cleavage by a γ-secretase inhibitor and inhibiting HER4 tyrosine kinase activity by neratinib decreased trastuzumab-induced HER4 nuclear translocation and enhanced trastuzumab response. There was also increased nuclear HER4 staining in the tumours from BT474 xenograft mice and human patients treated with trastuzumab. Furthermore, nuclear HER4 predicted poor clinical response to trastuzumab monotherapy in patients undergoing a window study and was shown to be an independent poor prognostic factor in HER2 positive breast cancer. Our data suggest that HER4 plays a key role in relation to trastuzumab resistance in HER2 positive breast cancer. Therefore, our study provides novel findings that HER4 activation, cleavage and nuclear translocation influence trastuzumab sensitivity and resistance in HER2 positive breast cancer. Nuclear HER4 could be a potential prognostic and predictive biomarker and understanding the role of HER4 may provide strategies to overcome trastuzumab resistance in HER2 positive breast cancer.

Neuregulin-activated ERBB4 induces the SREBP-2 cholesterol biosynthetic pathway and increases low-density lipoprotein uptake

Cholesterol is a lipid that is critical for steroid hormone production and the integrity of cellular membranes, and, as such, it is essential for cell growth. The epidermal growth factor receptor (EGFR) family member ERBB4, which forms signaling complexes with other EGFR family members, can undergo ligand-induced proteolytic cleavage to release a soluble intracellular domain (ICD) that enters the nucleus to modify transcription. We found that ERBB4 activates sterol regulatory element binding protein-2 (SREBP-2) to enhance low-density lipoprotein (LDL) uptake and cholesterol biosynthesis. Expression of the ERBB4 ICD in mammary epithelial cells or activation of ERBB4 with the ligand neuregulin 1 (NRG1) induced the expression of SREBP target genes involved in cholesterol biosynthesis, including HMGCR and HMGCS1, and lipid uptake, LDLR, which encodes the LDL receptor. Addition of NRG1 increased the abundance of the cleaved, mature form of SREBP-2 through a pathway that was blocked by addition of inhibitors of PI3K (phosphatidylinositol 3-kinase) or dual inhibition of mammalian target of rapamycin complex 1 (mTORC1) and mTORC2, but not by inhibition of AKT or mTORC1. Pharmacological inhibition of the activity of SREBP site 1 protease or of all EGFR family members (with lapatinib), but not EGFR alone (with erlotinib), impaired NRG1-induced expression of cholesterol biosynthesis genes. Collectively, our findings indicated that activation of ERBB4 promotes SREBP-2-regulated cholesterol metabolism. The connections of EGFR and ERBB4 signaling with SREBP-2-regulated cholesterol metabolism are likely to be important in ERBB-regulated developmental processes and may contribute to metabolic remodeling in ERBB-driven cancers.

Elevated Coexpression of KITENIN and the ErbB4 CYT-2 Isoform Promotes the Transition from Colon Adenoma to Carcinoma Following APC loss

PURPOSE AND EXPERIMENTAL DESIGN

The molecular events in the malignant progression of colon adenoma after loss of adenomatous polyposis coli (APC) are not fully understood. KITENIN (KAI1 C-terminal interacting tetraspanin) increases the invasiveness of colorectal cancer cells, and we identified a novel EGFR-independent oncogenic signal of EGF that works under coexpressed KITENIN and ErbB4. Here we tested whether elevated KITENIN and ErbB4 contribute to further progression of intestinal adenoma following APC loss.

RESULTS

The intestinal tissues of villin-KITENIN transgenic mice in which villin-driven KITENIN expression induces increased c-Jun expression exhibit mild epithelial cell proliferation but no epithelial lineage changes compared with those of nontransgenic mice. Among the four ErbB4 isoforms, JM-a/CYT-2 and JM-b/CYT-2 exhibited the highest AP-1 activity when cells coexpressing KITENIN and each isoform were stimulated by EGF. Interestingly, predominant overexpression of the ErB4-CYT-2 mRNA as well as increased EGFR expression were observed in intestinal adenoma of APC(min/+) mice, which makes the microenvironment of activated EGF signaling. When we crossed villin-KITENIN mice with APC(min/+) mice, intestinal tumor tissues in the crossed mice showed the characteristics of early-stage invading adenocarcinoma. In patients with colorectal cancer, ErbB4-CYT-2 mRNA expression was significantly greater in tumor tissues than in normal adjacent tissues, but no significant differences in tumor tissue expression were found between different colorectal cancer stages. Furthermore, the mRNA expression of KITENIN and that of ErbB4-CYT-2 were positively correlated in human colorectal cancer tissue.

CONCLUSIONS

Elevated coexpression of KITENIN and ErbB4-CYT-2 promotes the transition of colon adenoma to adenocarcinoma within an APC loss-associated tumor microenvironment.

Decreased LRIG1 in fulvestrant-treated luminal breast cancer cells permits ErbB3 upregulation and increased growth

ErbB3, a member of the ErbB family of receptor tyrosine kinases, is a potent activator of phosphatidyl inositol-3 kinase (PI3K) and mTOR signaling, driving tumor cell survival and therapeutic resistance in breast cancers. In luminal breast cancers, ErbB3 upregulation following treatment with the anti-estrogen fulvestrant enhances PI3K/mTOR-mediated cell survival. However, the mechanism by which ErbB3 is upregulated in fulvestrant-treated cells is unknown. We found that ErbB3 protein levels and cell surface presentation were increased following fulvestrant treatment, focusing our attention on proteins that regulate ErbB3 at the cell surface, including Nrdp1, NEDD4, and LRIG1. Among these, only LRIG1 correlated positively with ERα, but inversely with ErbB3 in clinical breast cancer datasets. LRIG1, an estrogen-inducible ErbB down-regulator, was decreased in a panel of fulvestrant-treated luminal breast cancer cells. Ectopic LRIG1 expression from an estrogen-independent promoter uncoupled LRIG1 from estrogen regulation, thus sustaining LRIG1 and maintaining low ErbB3 levels in fulvestrant-treated cells. An LRIG1 mutant lacking the ErbB3 interaction motif was insufficient to down-regulate ErbB3. Importantly, LRIG1 overexpression improved fulvestrant-mediated growth inhibition, while cells expressing the LRIG1 mutant were poorly sensitive to fulvestrant, despite effective ERα down-regulation. Consistent with these results, LRIG1 expression correlated positively with increased disease-free survival in anti-estrogen-treated breast cancer patients. These data suggest that ERα-dependent expression of LRIG1 dampens ErbB3 signaling in luminal breast cancer cells, and by blocking ERα activity with fulvestrant, LRIG1 is decreased thus permitting ErbB3 accumulation, enhanced ErbB3 signaling to cell survival pathways, and blunting therapeutic response to fulvestrant.

Deregulation of the EGFR/PI3K/PTEN/Akt/mTORC1 pathway in breast cancer: possibilities for therapeutic intervention

The EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway plays prominent roles in malignant transformation, prevention of apoptosis, drug resistance and metastasis. The expression of this pathway is frequently altered in breast cancer due to mutations at or aberrant expression of: HER2, ERalpha, BRCA1, BRCA2, EGFR1, PIK3CA, PTEN, TP53, RB as well as other oncogenes and tumor suppressor genes. In some breast cancer cases, mutations at certain components of this pathway (e.g., PIK3CA) are associated with a better prognosis than breast cancers lacking these mutations. The expression of this pathway and upstream HER2 has been associated with breast cancer initiating cells (CICs) and in some cases resistance to treatment. The anti-diabetes drug metformin can suppress the growth of breast CICs and herceptin-resistant HER2+ cells. This review will discuss the importance of the EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway primarily in breast cancer but will also include relevant examples from other cancer types. The targeting of this pathway will be discussed as well as clinical trials with novel small molecule inhibitors. The targeting of the hormone receptor, HER2 and EGFR1 in breast cancer will be reviewed in association with suppression of the EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway.

The localization of HER4 intracellular domain and expression of its alternately-spliced isoforms have prognostic significance in ER+ HER2- breast cancer

Human epidermal growth factor receptors (HERs) are known to play a pivotal role in breast cancer, both as prognostic markers and as therapeutic targets. The importance of Her4 expression is, however, still controversially discussed; there are few reports on the clinical significance of HER4, its splice variants, and cleaved HER4 intracellular domains (4ICD) which function differently depending on their localization in breast cancer. In 238 primary invasive breast cancer patients, we analyzed the expression levels of HER4 extracellular (JM-a and JM-b) and intracellular (CYT-1 and CYT-2) domains as well as 4ICD localization, and tested the relationship with clinicopathological characteristics and prognosis. The predominantly-expressed extracellular domain was JM-a, and lower CYT-2 dominance was a factor related to better relapse-free survival. CYT-2-dominance with higher nuclear 4ICD expression was a favorable prognostic marker especially in patients with the ER+ HER2- subtype treated with endocrine therapy. The absence of cytoplasmic 4ICD staining was related to better prognosis in CYT-1-dominant patients. In conclusion, analysis of splicing variants and 4ICD localization should be considered when targeting HER4 as a novel ER+/HER2- breast cancer treatment.